Investigation of Shortness of Breath

Initial Assessment and Red Flag Symptoms

• The American College of Radiology recommends that shortness of breath should be promptly investigated when it occurs at rest, with minimal exertion, is accompanied by concerning symptoms, or occurs in patients with risk factors for serious cardiopulmonary conditions 1, 2
• All acutely ill patients with shortness of breath should be assessed by measuring vital signs including respiratory rate, pulse rate, blood pressure, temperature, and oxygen saturation, according to the Thorax journal 3
• Oxygen saturation should be measured by pulse oximetry in all breathless and acutely ill patients, with the inspired oxygen device and flow rate recorded alongside the oximetry result, as recommended by the Thorax journal 3
• A recognized physiological "track and trigger" system such as the National Early Warning Score (NEWS) should be used for initial assessment and monitoring, according to the Thorax journal 3
• Shortness of breath accompanied by chest pain, especially in patients with risk factors for coronary artery disease, requires immediate investigation, as recommended by the American College of Cardiology 4
• Ripping chest pain, especially when sudden in onset and occurring in a hypertensive patient, suggests acute aortic syndrome and requires immediate investigation, according to the American College of Cardiology 4
• Shortness of breath with syncope or presyncope may indicate pulmonary embolism or serious cardiac pathology and requires immediate investigation, as recommended by the American College of Cardiology 4

Specific Patient Populations Requiring Investigation

• Patients with known or suspected COPD should be investigated when they report worsening breathlessness, especially when accompanied by increased sputum production or change in sputum color, according to the American Journal of Respiratory and Critical Care Medicine and the European Respiratory Journal 5, 6
• Patients >50 years of age who are long-term smokers with chronic breathlessness on minor exertion should be treated as having suspected COPD and require spirometric assessment, as recommended by the Thorax journal 7, 8
• Women presenting with shortness of breath are at risk for underdiagnosis of cardiac causes and should always have cardiac causes considered, according to the American College of Cardiology 4
• Patients with COPD, morbid obesity, cystic fibrosis, chest wall deformities, neuromuscular disorders, or bronchiectasis who develop worsening shortness of breath require urgent investigation including blood gas analysis, as recommended by the Thorax journal 7, 8

Diagnostic Approach Based on Duration

• Acute shortness of breath requires immediate assessment with vital signs, oxygen saturation, and focused cardiovascular examination, according to the Thorax journal 3
• Chest radiography should be performed promptly in patients with acute shortness of breath, though it has high specificity but low sensitivity for cardiac causes, as recommended by the American College of Radiology 1, 2
• If cardiac cause is suspected, echocardiography is recommended as an important tool to evaluate cardiac structure and function, according to the American College of Radiology 1, 2
• Spirometry should be performed to assess for airflow obstruction, particularly in patients with risk factors for COPD, as recommended by the American Journal of Respiratory and Critical Care Medicine and the European Respiratory Journal 5, 6
• The Modified Medical Research Council (mMRC) dyspnea scale should be used to assess the severity of functional dyspnea, according to the American Journal of Respiratory and Critical Care Medicine and the European Respiratory Journal 5, 6

Imaging Recommendations

• Chest X-ray is the initial imaging study for all patients with unexplained shortness of breath, as recommended by the American College of Radiology 1
• Transthoracic echocardiography should be performed in all patients with dyspnea of suspected cardiac origin, according to the American College of Radiology 1, 2
• CT of the chest is appropriate for patients with unexplained shortness of breath when pulmonary causes are suspected, as recommended by the American College of Radiology 1, 2
• CT angiography of the chest should be considered when pulmonary embolism is suspected, according to the American College of Radiology 1

Common Pitfalls to Avoid

• Failing to recognize that shortness of breath in elderly patients may present atypically with confusion, delirium, or falls rather than the classic complaint of breathlessness, as noted by the American College of Cardiology 4
• Overlooking cardiac causes of shortness of breath in women, who may present with atypical symptoms, according to the American College of Cardiology 4
• Administering high-concentration oxygen to patients with COPD or others at risk of hypercapnic respiratory failure, which can worsen respiratory acidosis, as recommended by the Thorax journal 7, 8
• Assuming that relief with nitroglycerin is diagnostic of myocardial ischemia; this should not be used as a diagnostic criterion, according to the American College of Cardiology 4

Emergency Department Approach to Shortness of Breath

Oxygen Therapy and Monitoring

• The British Thoracic Society recommends measuring oxygen saturation by pulse oximetry in all breathless patients and recording it as the "fifth vital sign" along with the inspired oxygen device and flow rate 9
• For patients without risk of hypercapnic respiratory failure, the target oxygen saturation is 94-98% 9
• For patients with risk of hypercapnic respiratory failure, the target oxygen saturation is 88-92% pending blood gas results 9
• Administering high-concentration oxygen to patients at risk of hypercapnic respiratory failure can worsen respiratory acidosis and outcomes 9

Condition-Specific Emergency Management

• The American Heart Association recommends administering inhaled bronchodilators (albuterol/salbutamol) immediately for patients with known asthma or COPD presenting with acute dyspnea and wheezing 10, 11
• If respiratory difficulty occurs with cutaneous manifestations (hives, lip/eye swelling) or cardiovascular effects (hypotension, shock), this represents anaphylaxis involving two or more body systems, and epinephrine autoinjector should be administered if available 10, 11

Diagnostic Workup and Critical Pitfalls

• Arterial blood gas is essential for patients at risk of hypercapnic respiratory failure to guide oxygen therapy 9
• Delaying assessment for sudden 3% oxygen saturation drop can lead to overlooking acute deterioration, and requires immediate reassessment 9
• Assuming normal pulse oximetry rules out serious pathology is incorrect, as in carbon monoxide poisoning, pulse oximetry will be falsely normal 9

Escalation of Care

• The British Thoracic Society recommends calling for intensive care consultation or activating resuscitation team for patients requiring oxygen therapy who cannot maintain target saturations 9
• Patients with signs of impending respiratory failure (altered mental status, inability to speak in full sentences, accessory muscle use) should have their care escalated 9
• Any patient triggering high-risk criteria on NEWS or similar scoring system should have their care escalated 9